Alpha olefins from lower alkene oligomers

ABSTRACT

Internally unsaturated near linear oligomers of lower olefins are converted into alpha olefins, or 1-alkenes, of essentially the same degree of linearity. The internally unsaturated olefins are the product of lower alkene oligomerization using a surface deactivated zeloite, such as ZSM-5 or ZSM-23, and contain about 1 to 2 methyl branches per twelve (12) carbon atoms. The feedstock is converted to alpha olefin oligomers which also contain approximately 1 to 2 methyl branches per thirteen (13) carbon atoms. The conversion is achieved by hydroformylation of the near linear internal olefins to provide a novel 1-alkanol oligomer structure without further branching of the carbon oligomeric chain. Acetylation of the 1-alkanol followed by deesterification by pyrolysis provides the sought for near linear 1-alkene. The near-linear oligomers of lower olefins so produced comprise vinyl hydrocarbon monomers that can be further oligomerized by cationic and coordination catalysts.

This invention relates to a process for the production of near linearhigher alpha olefins from olefinic oligomers prepared from lower alkenesMore particularly, the invention relates to a process for the conversionof near linear lower alkene oligomers containing internal olefinicunsaturation to alpha olefins by hydroformylation to 1-alkanols ofequivalent linearity, followed by esterification and pyrolysis to1-alkenes. The near linear alpha olefins so produced are useful, interalia, for the production of high quality synthetic lubricants.

BACKGROUND OF THE INVENTION

Recent work in the field of olefin upgrading has resulted in a catalyticprocess for converting lower olefins to heavier hydrocarbons. Heavydistillate and lubricant range hydrocarbons can be synthesized overZSM-5 type catalysts at elevated temperature and pressure to provide aproduct having substantially linear molecular conformations due to theellipsoidal shape selectivity of certain medium pore catalysts.

Conversion of olefins to gasoline and/or distillate products isdisclosed in U.S. Pat. Nos. 3,960,978 and 4,021,502 (Givens, Plank andRosinski) wherein gaseous olefins in the range of ethylene to pentene,either alone or in admixture with paraffins are converted into anolefinic gasoline blending stock by contacting the olefins with acatalyst bed made up of a ZSM-5 type zeolite. Particular interest isshown in a technique developed by Garwood, et al., as disclosed inEuropean patent application No. 83301391.5, published Sept. 29, 1983. InU.S. Pat. Nos. 4,150,062; 4,211,640 and 4,227,992 Garwood, et al.,disclose the operating conditions for the Mobil Olefin toGasoline/Distillate (MOGD) process for selective conversion of C₃ +olefins to mainly aliphatic hydrocarbons.

In the process for catalytic conversion of olefins to heavierhydrocarbons by catalytic oligomerization using a medium pore, shapeselective, acid, crystalline zeolite, such as ZSM-5 type catalyst,process conditions can be varied to favor the formation of hydrocarbonsof varying molecular weight. At moderate temperature and relatively highpressure, the conversion conditions favor C₁₀ + aliphatic product. Lowerolefinic feedstocks containing C₂ -C₈ alkenes may be converted; however,the distillate mode conditions do not convert a major fraction ofethylene A typical reactive feedstock consists essentially of C₃ -C₆mono-olefins, with varying amounts of nonreactive paraffins and the likebeing acceptable components.

U.S. Pat. Nos. 4,520,221, 4,568,786 and 4,658,079 to C. S. H. Chen, etal., incorporated herein by reference in their entirety, disclosefurther advances in zeolite catalyzed olefin oligomerization. Thesepatents disclose processes for the preparation of lubricant rangehydrocarbons by oligomerization of light olefins using zeolite catalystsuch as ZSM-5. The oligomers so produced are essentially linear instructure and contain 90% internal olefin unsaturation. These uniqueolefinic oligomers are produced by surface deactivation of the ZSM-5type catalyst by pretreatment with a surface-neutralizing base. Processconditions can be controlled to favor the recovery of near linear olefinoligomers containing six to twenty carbon atoms. Optionally, lubricantquality oligomers of higher carbon number can also be produced.

It is known that synthetic lubricating fluids of superior quality can beproduced by oligomerization of 1-alkenes, particularly 1-decene.Building on that prior art resource, oligomers of 1-alkenes from C₆ toC₂₀ have been prepared, with commercially useful synthetic lubricantsfrom 1-decene oligomerization yielding a distinctly superior lubricantproduct via either cationic, Ziegler or chromium catalyst known to beeffective in the polymerization of 1-alkenes.

Theoretically, the oligomerization of 1-decene, for example, tolubricant oligomers in the C₃₀ and C₄₀ range can result in a very largenumber of structural isomers. Characterizing those oligomers thatproduce a preferred and superior synthetic lubricant meeting thespecification requirements of wide-temperature fluidity whilemaintaining low pour point represents a prodigious challenge to theworkers in the field. Brennan, Ind. Eng. Chem. Prod. Res. Dev. 1980, 19,2-6, cites 1-decene trimer as an example of a structure compatible withstructures associated with superior low temperature fluidity wherein theconcentration of atoms is very close to the center of a chain of carbonatoms.

One characteristic of the molecular structure of 1-alkene oligomers thathas been found to correlate very well with improved lubricant propertiesin commercial synthetic lubricants is the ratio of methyl to methylenegroups in the oligomer. The ratio is called the branch ratio and iscalculated from infra red data as discussed in "Standard Hydrocarbons ofHigh Molecular Weight", Analytical Chemistry, Vol. 25, no. 10, p. 1466(1953). Viscosity index has been found to increase with lower branchratio. Oligomers prepared from 1-decene by cationic polymerization havebranch ratios of greater than 0.20. Those prepared by chromium orZiegler catalyzed oligomerization have lower branch ratios. Whether byrearrangement, isomerization or a yet to be elucidated mechanism, it isclear that in the art of 1-alkene oligomerization to produce syntheticlubricants as practiced to-date branching occurs and constrains thelimits of achievable lubricant properties, particularly with respect toviscosity index Obviously, increased branching increases the number ofisomers in the oligomer mixture, orienting the composition away from thestructure which would be preferred from a consideration of thetheoretical concepts accepted in the art.

In view of the foregoing, the practice in the synthetic lubricants fieldhas been to oligomerize linear 1-alkene, more particularly singlecompounds such as 1-decene, in order to help control branching and thenumber of oligomeric species in the lubricant fluid. However, 1-deceneand similar 1-alkenes are expensive and produce expensive lubricantfluids. Unfortunately, potentially less expensive olefins from theprocess of Chen, et al., are largely internal olefins and are alsosightly branched, where unbranched alpha olefins are preferred. Theirinternal olefin structure also does not lend itself to oligomerizationwith either Ziegler-Natta or chromium catalysts used to produce veryhigh quality synthetic lubricants. Cationic catalysts, e.g., BF₃ orAlCl₃ complexes, polymerize internal olefins but result in more branchedor lower VI lubes.

Accordingly, it is an object of the present invention to provide aprocess for the conversion of slightly branched internal olefinoligomers, prepared from lower alkenes using surface deactivated zeolitecatalyst, to alpha olefins or 1-alkenes.

Another object of the present invention is to provide a process forconverting the aforementioned internal olefins to alpha olefins whileretaining the low degree of branching in the internal olefin.

Yet another object of the instant invention is to prepare novel slightlybranched 1-alkanol compositions from said internal olefins.

A further object of the present invention is to provide a process forproduction of less expensive 1-alkenes useful in the preparation of highquality polyalphaolefin (PAO) synthetic lubricant fluids.

SUMMARY OF THE INVENTION

An integrated series of process steps has been discovered thateffectively converts internally unsaturated near linear oligomers oflower olefins into alpha olefins, or 1-alkenes, of essentially the samedegree of linearity. The internally unsaturated olefins are the productof lower alkene oligomerization using a surface deactivated zeolite,such as ZSM-5 or ZSM-23, and contain about 1 to 2 methyl branches perfifteen carbon atoms. This feedstock is converted in the presentinvention to alpha olefin oligomers which also contain approximately 1to 2 methyl branches per fifteen carbon atoms. The conversion isachieved by hydroformylation of the near linear internal olefins toprovide a novel 1-alkanol oligomer structure without further branchingof the carbon oligomeric chain. Acetylation of the 1-alkanol followed bydeesterification by pyrolysis provides the sought for 1-alkene, withoutincreasing the non-linearity of the 1-alkanol. The acetylation can beachieved in situ during the pyrolysis by cofeeding acetic anhydride andthe 1-alkanol. In this manner, near-linear oligomers of lower olefinsare converted to vinyl hydrocarbon monomers that can be furtheroligomerized by cationic and coordination catalysts.

More particularly, a process is disclosed for the production of nearlinear 1-alkene comprising vinyl hydrocarbon monomer, or a mixture ofvinyl monomers, from near linear lower alkene oligomer having betweensix and twenty carbon atoms and containing internal olefinicunsaturation. The process comprises reacting the oligomer, or a mixtureof oligomers, with H₂ and CO mixture in contact with a hydroformylationcatalyst under hydroformylation conditions sufficient to convert theoligomer to aliphatic 1-alkanol. The 1-alkanol contains a methyl tomethylene branch ratio equal to or less than the oligomer. The 1-alkanolis recovered by conventional means and converted to an ester underesterification conditions in contact with an aliphatic acylating agent.The ester is recovered and deesterified by pyrolyzing the ester underconditions sufficient to produce 1-alkene comprising near linear vinylhydrocarbon monomer, or a mixture of monomers.

Preferably, the oligomer comprises the oligomerization product of C₃ -C₅alkene in contact with surface deactivated, acidic, shape selective,medium pore metallosilicate and has a methyl to methylene branch ratioless than 0.21. The hydroformylation is carried out using a stericallyhindered catalyst such as Co₂ (CO)₆ [(n--C₄ H₉)₃ P]₂.

The invention also provides a novel mixture of near linear aliphatic1-alkanols containing between six and twenty carbon atoms and having amethyl to methylene branch ratio less than 0.21. Preferably, thealkanols comprise C₉ -C₁₂ 1-alkanols having a methyl to methylene branchratio less than 0.18.

DETAIL DESCRIPTION OF THE INVENTION

Near linear alpha olefins are produced in the present inventionaccording to the following general sequence of reactions where R is theolefin oligomer hydrocarbyl moiety: ##STR1##

NEAR-LINEAR OLEFIN

The olefin oligomers used as starting material in the present inventionare prepared from C₃ -C₅ olefins according to the methods presented byChen, et al., in the aforementioned patents cited and N. Page and L.Young in allowed application Ser. No. 105,438, filed Oct. 7, 1987 andincorporated herein as references. Shape-selective oligomerization, asit applies to conversion of C₃ -C₅ olefins over ZSM-5, is known toproduce higher olefins up to C₃₀ and higher. Reaction conditionsfavoring higher molecular weight products are low temperature (200°-260°C.), elevated pressure (about 2000 kPa or greater) and long contacttimes (less than 1 WHSV). The reaction under these conditions proceedsthrough the acid catalyzed steps of oligomerization,isomerization-cracking to a mixture of intermediate carbon numberolefins, and interpolymerization to give a continuous boiling productcontaining all carbon numbers. The channel system of ZSM-5 typecatalysts impose shape selective constraints on the configuration oflarge molecules, accounting for the differences with other catalysts

The shape-selective oligomerization/polymerization catalysts preferredfor use herein to prepare the olefin oligomers used as starting materialin the invention include the crystalline aluminosilicate zeolites havinga silica to alumina molar ratio of at least 12, a constraint index ofabout 1 to 12 and acid cracking activity of about 50-300. Representativeof the ZSM-5 type zeolites are ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35 andZSM-38. ZSM-5 is disclosed and claimed in U.S. Pat No. 3,702,886 andU.S. Pat. No. Re. 29,948; ZSM-11 is disclosed and claimed in U.S. Pat.No. 3,709,979. Also, see U.S. Pat. Nos. 3,832,449 for ZSM-12; 4,076,842for ZSM-23; 4,016,245 for ZSM-35 and 4,046,839 for ZSM-38. Thedisclosures of these patents are incorporated herein by reference. Asuitable shape selective medium pore catalyst for fixed bed is a smallcrystal H-ZSM-5 zeolite (silica:alumina ratio=70:1) with alumina binderin the form of cylindrical extrudates of about 1-5 mm. Unless otherwisestated in this description, the catalyst shall consist essentially ofZSM-5, which has a crystallite size of about 0.02 to 0.05 micron, orZSM-23. Other pentasil catalysts which may be used in one or morereactor stages include a variety of medium pore siliceous materialdisclosed in U.S. Pat. Nos. 4,414,423 and 4,417,088, incorporated hereinby reference.

The acid catalysts are deactivated by pretreatment with asurface-neutralizing base, as disclosed by Chen, et al., and Page, etal., in the patent and allowed application incorporated by reference.Surface deactivation is carried out using bulky or sterically hinderedbases, typically those comprising trialkyl substituted pyridines. Thesehindered bases have very limited access to the internal pore structureof the catalyst, leaving the pores active sites for near linearoligomerization. However, active surface sites which are notconstrained, as pores are, to low branching oligomerization areneutralized.

Considering propylene oligomerization for purposes of illustration, theolefinic oligomerization-polymerization products include C₁₀ +substantially linear aliphatic hydrocarbons. The ZSM-5 catalytic pathfor propylene feed provides a long chain with approximately one loweralkyl (e.g., methyl) substituent per 8 or more carbon atoms in thestraight chain.

When propylene or butene are oligomerized according to processesdescribed herein, a unique mixture of liquid hydrocarbon products areformed. More particularly, this mixture of hydrocarbons may comprise atleast 95% by weight of mono-olefin oligomers of the empirical formula:

    C.sub.n H.sub.2n

where n is 3 to 30, the mono-olefin oligomers comprising at least 20percent by weight of olefins having at least 12 carbon atoms, theolefins having at least 12 carbon atoms having an average of from 0.80to 2.00 methyl side groups per carbon chain, the olefins not having anyside groups other than methyl.

It will be understood that methYl side groups are methyl groups whichoccupy positions other than the terminal positions of the first and last(i.e., alpha and omega) carbon atoms of the longest carbon chain. Thislongest carbon chain is also referred to herein as the carbon backbonechain of the olefin. The average number of methyl side groups for theC₁₂ olefins may comprise any range with the range of 0.80 to 2.00.

These oligomers may be separated into fractions by conventionaldistillation separation When propylene is oligomerized, olefin fractionscontaining the following number of carbon atoms can be obtained 6, 9,12, 15, 18 and 21. When butene is oligomerized, olefin fractionscontaining the following numbers of carbon atoms may be obtained 8, 12,16, 20, 24 and 28. It is also possible to oligomerize a mixture ofpropylene and butene and to obtain a mixture of oligomers having atleast 6 carbon atoms.

Page and Young (allowed application Ser. No. 105,438, filed Oct. 7,1987) described these new olefins as multi-component mixtures ofpropylene oligomers having relatively few branching methyl groups on thecarbon backbone. As an example of branching, the dodecene fractionprepared from propylene and HZSM-23 surface modified by collidine[ZSM-23-dodecenes] typically has 1.3 methyl branches. This can bereduced to 1.0 or less by varying reaction conditions.

HYDROFORMYLATION

Hydroformylation, a rhodium or cobalt catalyzed addition of carbonmonoxide and hydrogen gas to an olefin, produces aldehydes. See J.Falbe, New Syntheses with Carbon Monoxide, New York (1980); E. J.Wickson, Monohydric Alcohols, ACS Symposium Series 159, Washington, D.C.(1981); Ford, P. C., Catalytic Activation cf Carbon Monoxide, ACSSymposium Series 152, Washington, D. C. (1981), all references herebyincorporated by reference. However, Slaugh and Mullineaux discoveredthat hydroformylations using complexes of tri-n-butylphosphine andcobalt carbonyl catalyze the conversion of olefins directly to alcohols(i.e., the initially formed aldehydes concurrently hydrogenate). Also,the new alcohol function (--CH₂ OH) bonds predominately on the carbonchain-end. See Slaugh, L., Mullineaux, R. D., HydroformylationCatalysts, J. Organomet. Chem., 13, 469-477 (1968); U.S. Pat. Nos.3,239,569; 3,239,570; 3,329,566; 3,488,158; and 3,488,157, allreferences hereby incorporated by reference. This permits using avariety of internal olefins as feeds, because they isomerize to aterminal position before hydroformylating. In contrast, rhodium-basedcatalysts do not promote olefin isomerization, and hydroformylationoccurs predominately on the original double bond. See Asinger, F., Fell,B., Rupilius, W., Hydroformylation of 1-Olefins in TertiaryOrqanophosphine-Colbalt Hydrocarbonyl Catalyst Systems, Chem. ProcessDes. Dev., 8(2), 214 (1969); Stefani, A., Consiglio, G., Botteghi, C.,Pino, P., Stereochemistry of the Hydroformylation of OlefinicHydrocarbons with Cobalt and Rhodium Catalysts, J. Amer. Chem. Soc.,99(4), 1058-1063.

ESTERIFICATION

The formation of esters from primary alcohols analogous to thehydroformylation product of the near-linear olefins described above is areaction well known in the art. The 1-alkanols used in the presentinvention can be converted to esters using acylating agents that includealiphatic carboxyl acids, acyl halides, carboxyl acid anhydrides orcorboxyl acid esters. Other, less common, routes to esterification mayalso be used such as those using ketenes and alcoholysis of nitriles.The art is well described in "Synthetic Organic Chemistry" by Wagner andZuck, published by John Wiley and Sons, pages 480-498, incorporatedherein by reference.

Acylating agents used in the present invention comprise aliphaticcarboxyl acids and derivatives thereof having C₁ -C₂₀ carbon atoms,particularly carboxyl acid anhydrides. The preferred acylating agent isacetic anhydride which converts the primary alcohol of the invention tothe acetate ester. The reaction is typically carried out in the presenceof a catalyst such as small amounts of sulfuric acid, sodium acetate,pyridine or Al₂ O₃. Generally, the esters are formed using carboxyl acidderivatives containing 2 to 6 carbon atoms and, in addition to aceticacid, include proprionic and buturic acid.

PYROLYSIS

The final synthetic step in the synthesis of the alpha-olefins accordingto the present invention involves the conversion of the aforementionedesters to the alpha-olefin by pyrolysis or deesterification. It is knownin the art that olefins, including alpha-olefins can be produced bydehydration of primary alcohols typical of those produced in thisinvention. However, an important consideration in the present inventionis to conduct all the processes including this final synthetic stepwithout increasing the branching of the oligomeric molecule. Maintaininglinearity in order to produce near-linear alpha-olefins is an importantpart of the overall inventive concept. Directly dehydrating the alkanolcan, in some cases, lead to isomerization which may increase branching.This possibility is obviated by preparing the alpha-olefin bydeesterification which does not result in isomerization or increasedbranching of the alpha-olefin.

The pyrolysis of esters to olefins is known in the art and described in"Synthetic Organic Chemistry" by Wagner and Zuck, John Wiley and Son,Publisher, pages 41-42, incorporated herein by reference. Pyrolysis canbe carried out at temperatures between 300°-750° C. to yield the olefin,in this case alpha-olefin, in high yield.

As previously described herein the near-linear olefins used as startingmaterial in this invention are typically prepared comprising a mixtureof olefins containing a wide range of carbon numbers. The startingmaterial may be used in this condition to produce a mixture of1-alkanols and alpha-olefins containing a wide range of carbon numbers.Optionally the near-linear olefins can be separated by distillation orother means common and known in the art to narrow the range of carbonnumbers in the starting material. For purposes of utilizing the presentinvention to prepare alpha-olefins suitable for oligomerization tosynthetic lubricants carbon numbers in the range of C₉ -C₁₂ arepreferred. A more particularly preferred carbon number for analpha-olefin is 1-decene.

The following prophetic Examples are presented to illustrate the overallprocess of the present invention and are not intended to limit the scopeof the invention.

EXAMPLE 1

(a) Near-linear olefins are prepared from propylene or isobutene orrefinery mixtures of propylene, butenes, propane and butanes using2,6-di-tert-butylpyridine surface deactivated HZSM-5B as the shapeselective catalyst according to the procedure described in U.S. Pat. No.4,520,221.

(b) The above olefins are hydroformylated at 180° C. using a mixture ofcarbon monoxide and hydrogen and Co₂ (CO)₆ [(n--C₄ H₉)₃ P]₂ as catalyst.The hydroformylation is carried out under these conditions for a periodof time sufficient to convert the near-linear olefins starting materialto a mixture of 1-alkanols.

(c) The 1-alkanols from (b) are separated by distillation and esterifiedusing acetic acid and A₂ O₃ as catalyst to produce the acetate ester ofthe 1-alkanols.

(d) The acetate esters prepared in (c) are separated and pyrolyzed at500° C. over pyrexhelices to produce a mixture of alpha-olefins having amethyl to methylene branch ratio of 0.15 to 0.25.

EXAMPLE 2

(a) Near-linear olefins with 1 to 2 methyl branches per 12 carbon atomsare prepared by propylene or refinery mixtures of propylene, butenes,propane and butane using 2,4,6-collidine modified HZSM-23 as the shapeselective catalyst according to procedures described by Page and Youngin the reference previously cited herein. Hydroformylation,esterification and pyrolysis steps are carried out as described in steps(b), (c) and (d) in Example 1. The alpha olefins produced have a methylto methylene branch ratio of 0.1 to 0.2.

EXAMPLE 3

1-alkanols are prepared as described in step (b) of Example 1. In acontinuous process the 1-alknaols are reacted with an excess of aceticanhydride and passed over silica at 600° C., in a nitrogen atmosphere,to pyrolyze the acetate ester formed in situ to alpha-olefins having amethyl to methylene branch ratio of 0.15 to 0.25.

EXAMPLE 4

1-alkanols are prepared as described in step (b) of Example 2. In acontinuous process the 1-alkanols are reacted with an excess of aceticanhydride and passed over silica at 600° C., in a nitrogen atmosphere,to pyrolyze the acetate formed in situ to alpha olefins having a methylto methylene branch ration of 0.1 to 0.2.

The branch ratios defined as the ratios of CH₃ groups to CH₂ groups arecalculated from the weight fractions of methyl groups obtained byinfrared methods, published in Analytical Chemistry. Vol. 25, No. 10, p.1466 (1953). ##EQU1##

While the instant invention has been described by specific examples andembodiments, there is no intent to limit the inventive concept except asset forth in the following claims.

What is claimed is:
 1. A process for the production of near linear1-alkene from near linear lower alkene oligomer having between six andtwenty carbon atoms, said oligomer containing internal olefinicunsaturation, comprising;reacting said oligomer with H₂ and CO mixturein contact with a hydroformylation catalyst under hydroformylationconditions sufficient to convert said oligomer to aliphatic 1-alkanol,said alkanol having a methyl to methylene branch ratio equal to or lessthan said oligomer; recovering and converting said 1-alkanol to an esterunder esterification conditions in contact with aliphatic acylatingagent; recovering and pyrolyzing said ester under conditions sufficientto produce said 1-alkene.
 2. The process of claim 1 wherein saidoligomer comprises the oligomerization product of C₃ -C₅ alkene incontact with surface deactivated, acidic, shape selective, medium poremetallosilicate.
 3. The process of claim 2 wherein said oligomercomprises the oligomerization product of propylene.
 4. The process ofclaim 1 wherein said oligomer and said 1-alkene methyl to methylenebranch ratio is less than 0.25.
 5. The process of claim 4 wherein saidratio is between 0.1 and 0.2.
 6. The process of claim 1 wherein thebranch ratio of said 1-alkene is not greater than that of said oligomer.7. The process of claim 1 wherein said oligomer comprises C₉ -C₁₂hydrocarbon having methyl to methylene branch ratio of less than 0.18.8. The process of claim 1 wherein said hydroformylation catalystcomprises one of rhodium, cobalt and ruthenium.
 9. The process of claim7 wherein said catalyst comprises Co₂ (CO)₆ [(n--C₄ H₉)₃ P]₂.
 10. Theprocess of claim 1 wherein the H₂ /CO ratio is in the range of 0.5:1 to5:1.
 11. The process of claim 10 wherein said ratio is about 1.8 to 1.12. The process of claim 1 wherein said hydroformylation conditionscomprise temperature between 250° and 150° C.
 13. The process of claim12 wherein the temperature is about 181° C.
 14. The process of claim 1wherein said acylating agent comprises aliphatic carboxylic acid,anhydride, halide or ester having 2 to 20 carbon atoms.
 15. The processof claim 1 wherein said acylating agent comprises acetic anhydride andsaid ester comprises acetate.
 16. The process of claim 1 wherein saidester is pyrolyzed at a temperature between 200° and 800° C.
 17. Theprocess of claim 16 wherein the temperature is about 500° C.
 18. Amixture of near linear 1-alkenes having between seven and twenty-onecarbon atoms, said alkenes comprising the reaction product of theprocess comprising;reacting a feedstock comprising near linear loweralkene oligomers having between six and twenty carbon atoms, saidoligomers containing internal olefinic unsaturation, with H₂ and COmixture in contact with a hydroformylation catalyst underhydroformylation conditions sufficient to convert said oligomers to nearlinear aliphatic 1-alkanols, said alkanols having a methyl to methylenebranch ratio equal to or less than said oligomers; recovering andconverting said 1-alkanols to esters under esterification conditions incontact with aliphatic acylating agent; recovering and pyrolyzing saidesters under conditions sufficient to produce said 1-alkenes.
 19. Themixture of claim 18 wherein said oligomers contain between nine andtwelve carbon atoms and said 1-alkenes comprise C₁₀ -C₁₃ 1-alkeneshaving a methyl to methylene branch ratio of less than 0.18.
 20. Themixture of claim 18 wherein said hydroformylation catalyst comprises oneof rhodium, cobalt and ruthenium.
 21. The mixture of claim 20 whereinsaid catalyst comprises Co₂ (CO)₆ [(n--C₄ H₉)₃ P]₂.
 22. The mixture ofclaim 20 wherein the H₂ /CO ratio is in the range of 0.5:1 to 5:1. 23.The mixture of claim 22 wherein said ratio is about 1.8 to
 1. 24. Themixture of claim 18 wherein said hydroformylation conditions comprisetemperature between 250° and 150° C.
 25. The mixture of claim 24 whereinthe temperature is about 181° C.
 26. The mixture of claim 18 whereinsaid acylating agent comprises aliphatic carboxylic acid, anhydride,halide or ester having 2 to 20 carbon atoms.
 27. The mixture of claim 18wherein said acylating agent comprises acetic anhydride and said estercomprises acetate.
 28. The mixture of claim 18 wherein said ester ispyrolyzed at a temperature between 200° and 800° C.
 29. The process ofclaim 28 wherein the temperature is about 500° C.